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XXI. Gbfervations on the Genus of Pore/la, and! the Phafcum caulefcem 

 of Linnaus. By Mr. James Dick/on , F. L. & 



Read May 5, 1795. 



THE genns of Porella, firft eftablifhed by Dillenius, and from 

 him copied by Linnaeus, who never faw the plant, had long 

 appeared to me to be very doubtful : I had, however, an oppor- 

 tunity, fome time ago, of fatisfying myfelf on this fubject. I 

 happened to receive fome mofTes as package to plants from Ame- 

 rica; and, upon examining them, found a Jungermannia and a 

 Splacknum in fructification. I fufpected the Jungermannia to be the 

 fame with the Porella of Dillenius ; but this could not be afcertained 

 without actually comparing the two fpecimens, which I had an 

 opportunity of doing by the indulgence of Dr. Sibthorp, of Oxford, 

 who permitted me to compare my mofTes with Dillenius's original 

 collection; and, upon the raoft careful 'examination, I found my 

 Jungermannia to agree exactly with his Porella, but could find no 

 fructification upon his fpecimen. 



As I have no doubt that my Jungermannia and his Porella are one 

 and the fame plant, I fhall next endeavour to trace how Dillenius 

 has fallen into this error ; for the plant has exactly the habit of 

 a Jungermannia, — This was, probably, by receiving an imperfect 

 fpecimen ; as the vagina, when damaged either by the weather or 

 by infects, after the tender flower had fallen off, would very much 

 refemble the capfule which he has figured. 



His figure of the plant is too much crowded with leaves ; but in 

 his original drawings in the pofTefTion of Sir Jofeph Banks, the 



• 6 leaves, 



